Speciation (biology only) — AQA GCSE Biology
Test yourself on Speciation (biology only) with AQA GCSE practice questions.
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Speciation (biology only) explained
Wallace is particularly remembered for two connected areas of work.
Read the full explanation
First, he studied warning colouration, where prey animals have bright, conspicuous patterns that predators learn to avoid because the prey is toxic or dangerous. He also described mimicry, where a harmless species resembles a warningly coloured species and gains protection. Second, he developed ideas about speciation: populations that become separated can accumulate different variations, and over many generations they may become so different that they can no longer interbreed to produce fertile offspring. His island observations supported this because related species on different islands showed distinct features. Students should be able to explain both the warning colouration idea and the role of isolation and selection in forming new species, using examples such as brightly coloured frogs or insects.
Your focus
- Describe how warning colouration protects an organism from predators.
- Explain the role of isolation and selection in speciation.
- Distinguish between warning colouration, camouflage and mimicry.
Speciation (biology only) exam tips
Marking Points
- Warning colouration makes a toxic or dangerous organism conspicuous to predators.
- Predators learn to associate the bright pattern with an unpleasant experience and avoid similar prey.
- Mimicry occurs when a harmless species resembles a warningly coloured species and gains protection.
- Speciation involves populations becoming reproductively isolated so that gene flow between them stops.
- Different selection pressures in separated environments cause different variations to be favoured.
- Over many generations the separated populations become sufficiently different to be classified as different species.
Examiner Tips
- 💡Use the term reproductive isolation and explain that the populations can no longer interbreed to produce fertile offspring.
- 💡When describing warning colouration, state the benefit to the prey and the learning response of the predator.
- 💡Keep the example brief and relevant, such as a brightly coloured toxic frog, rather than writing a long story.
Common Mistakes
- Confusing warning colouration with camouflage; correction: warning colouration is conspicuous and advertises danger, whereas camouflage helps an organism blend in.
- Thinking speciation happens in a single generation; correction: speciation requires many generations of variation, selection and reproductive isolation.
- Believing that isolation alone creates new species; correction: isolation must be followed by different selection pressures and genetic changes over time.